There have been known lighting devices with a directed light, the so-called controlled scanning devices, comprising a case which includes a light source, a unit of controlled effects and an objective. On the outside part of the case, there is installed a controlled mirror as a light guiding apparatus. A beam from the light source, through the unit of effects and the objective, falls on the mirror mounted to rotate about the beam axis and about an axis perpendicular to the beam axis [see, for example, the advertising booklet "Super Scan ZOOM", CLAY PAKY Professional Show Lighting, 1994].
Changing the mirror turning angles about two axes by means of turning mechanisms results in the change of a light beam direction. The controlled scanning device possesses the effect of a beam movement in the space (the beam scanning), the effect of a local lighting of the object in the space, the color beam effect and the template position effect.
A major disadvantage of the controlled scanning devices with a scanning mirror is that a working space in which the objects are within reach of the beam is greatly limited due to the impossibility to increase the mirror turning angles, especially about an axis perpendicular to the beam axis.
There has been known the use of light guides made of fiber bundles with a relative position of fibers at both ends being equal, for example, in the device for transmitting and zooming an image [see, for example, the USSR Inventors' Certificate No. 1,430,928 A1 G02B 6/06, 1988]. This device comprises a regular light guide bundle with planar rectangular ends which functions as a light guiding apparatus. At a small input end face, light guides are tightly packed in strings, said strings being packed without a gap. At a large output end face, strings are packed with a gap. At the output end face, light guides in the strings are tightly packed, said strings being equidistant from each other. The light guide ends at the output end face are made scattering; opposite thereof, there are mounted cylindrical lenses with their generatrixes being parallel with the strings.
This device is used for zooming an image, particularly for displaying slides and an enlarged TV image.
A disadvantage of the device for transmitting and zooming an image is that it may not be used for transmitting a locally directed light transmission and image projection on the plane.
The closest prior art has been disclosed in a light guiding apparatus employed in an ornamental luminaire [see, the USSR Inventors' Certificate No. 1,555,598 A1 F21P 3/00, 1990]. This apparatus comprises a bundle of fiber light guides. Light guides are fastened together at one end, thus forming an input end face. The input end face is mounted to rotate about its own axis; the entire bundle may rotate, too. Output end faces of the light guides form a spherical surface. In so doing, one may achieve the effect of changing a position of luminous light guide end faces from the center of said spherical surface to the periphery thereof.
Advantages with this apparatus reside in the possibility of producing a spacious light effect and simplicity of the design.
Major drawbacks associated with the apparatus are that it allows no possibility to produce a focused beam due to the absence of a single output end face, no possibility to project an image on the plane and to control the beam.